Pennsylvania - Role: Building
| Nitre Hall |
| Noble, J. L. School |
| Nook, The |
| Noon, Philip, House |
| Normandy Farmstead |
| North Broad Street Station, Reading Company |
| Northeast Manual Training School |
| Northern National Bank |
| Northern Saving Fund and Safe Deposit Company |
| North Scranton Junior High School |
| Northumberland County Courthouse |
| Noxen School |
| N. Snellenburg Company Department Store Warehouse |
| Nugent Home for Baptists |
| Nutt, Adam Clarke, Mansion |
| Nutting Hall |
| Nyce Farm |
| Oakdale |
| Oakdale Public School |
| Oak Hill Estate |
| Oakland Public School |
| Oaklands |
| Oakley, Violet, Studio |
| Oaks Cloister |
| O'Connor, J.S., American Rich Cut Glassware Factory |
| Octagon Stone Schoolhouse |
| O'Donel House and Farm |
| Ogden House |
| Ogontz Hall |
| O'Hara, John, House |
| Ohringer Building |
| Oil City Armory |
| Old Brown's Mill School |
| Old City Hall |
| Old Customshouse |
| Old Dry Road |
| Old Federal Reserve Bank |
| Old Heidelberg Apartments |
| Old Homestead |
| Old Hoopes School |
| Old Indiana County Courthouse |
| Old Indiana County Jail and Sheriff's Office |
| Old Kennett Meetinghouse |
| Old Lehigh County Courthouse |
| Old Main |
| Old Main and Chemistry Building |
| Old Main at the Lutheran Home at Topton |
| Old Main, California State College |
| Old Main, Goethean Hall, and Diagnothian Hall |
| Old Norriton Presbyterian Church |
| Old Rose Tree Tavern |
| Old Swede's House |
| Old Union County Courthouse |
| Old Waterworks |
| Old West, Dickinson College |
| Old White Mill |
| Oliver, David P., High School |
| Oller, Joseph J., House |
| Olney Elementary School |
| Olney High School |
| Oregon Mill Complex |
| Ormrod, George, House |
| Orris, Adam, House |
| Orthodox Meetinghouse |
| Ortlieb, Henry F., Company Bottling House |
| Orton, Almerion C. & Barbara Moseman, Farm |
| Osterling, Frederick J., Office and Studio |
| Ostheimer, Martha and Maurice, Estate |
| Otto Eisenlohr and Bros Cigar Factory |
| Overbrook Gardens Apartments |
| Overbrook High School |
| Overbrook School |
| Oxford Hotel |
| Oyer, Christian, Jr., House |
| Packard Motor Corporation Building |
| Packer, Asa, Mansion |
| Packer, Harry, Mansion |
| Packer, Isaac A., Farm |
| Packer Memorial Chapel |
| Packwood House-American Hotel |
| Pagoda |
| Painter’s Folly |
| Painter, William, Farm |
| Palmer, Amos, House |
| Pardee, Israel Platt, Mansion |
| Park Dinor |
| Parker Dam State Park-Octagonal Lodge |
| Parkersville Friends Meetinghouse |
| Parkesburg National Bank |
| Parkesburg School |
| Parkhurst Memorial Presbyterian Church |
| Parkinson, Robert, Farm |
| Park Place School |
| Parkside Chapel |
| Park Towne Place |
| Parreco, James, House |
| Parsons-Taylor House |
| Passavant House |
| Passmore, Mansel, House |
| Passtown Elementary School |
Data from United States Park Service and Wikidata
